Premature birth is one of the principal causes of perinatal morbidity and mortality. In order of to aid in the understanding and prevention of this problem, it is imperative to elucidate the factors involved in the regulation of myometrial contractility and the initiation of parturition. Due to ethical considerations, data obtained from human studies are incomplete. This proposal will examine the role of CATS in the initiation of labor by studying the qualitative and quantitative changes in CAT concentrations in the chronically catheterized rhesus monkey. Studies will include measurements of epinephrine, and dopamine in maternal and fetal plasma and amniotic fluid. In addition, PG concentrations (PGEM-II, PGFM, and 6-keto-PGF1alpha) will be quantitated. How these changes are related to alterations in uterine activity and the initiation of labor will also be assessed. In vitro superfusion studies will examine the interaction between CATS and PGs in reproductive tissues collected from pregnant rhesus monkeys. Specifically, what are the stimulatory effects of CATS on PG biosynthesis by decidua, myometrium, amnion, and chorion? PG (PGF2, PGE2 and 6-keto-PGF1alpha) production will be quantitated before and after exposure of the tissue to CATs. These studies will be directed to answer the following questions: 1) Is there a causal relationship between changes in CATS and uterine activity rhythms? 2) Do CATs exert their effects indirectly by first stimulating PG biosynthesis? These studies are in line with the long-term goals of the present research program, namely, to clarify the mechanisms involved in the regulation of uterine contractility and the initiation of labor.